This approach has a few benefits over storing them in yaml, ini, json, etc.
Firstly, it stops you from commiting sensitive information into version control
- which it kind of feels weird even saying you should be using if you're not.
Secondly, it allows your configuration to vary substantially across
deployments - something it will inevitably have the tendency to do.

Now if you're following this approach then the question inevitably arises as to
how you're going to execute the app with a given configuration when you run it
from the command-line. The following is a simple solution invented with some
help from my colleagues at plug.dj (EDIT:
Jon pointed out to me we were doing something
similiar at SHIFT) - just write a simple shell script for
every environment you deploy to like so: